Nowadays each individual is in possession of a certain number of a wide variety of “cards”, e.g. an identity card, a bank card, a Social Security card, etc., all of which may be characterized firstly by a function they perform, and secondly by means they use to recognize the individual. Thus, traditional identity cards enable individuals to prove their identities during checks, providing third parties making the checks recognize the individuals from photographs on the cards. Likewise, bank cards enable individuals to make purchases, providing the individuals are in a position to provide respective confidential codes associated with each bank card.
Proposals have also been made to replace conventional recognition means with biometric recognition means. A card is then provided with a chip containing previously acquired biometric data of the individual, which data is representative of a physical characteristic of that individual (fingerprints, retina or iris of an eye, etc.). When an individual presents such a card, the individual is recognized by acquiring that individual's biometric data once more and then comparing the acquired data with the data in the card. For example, a French biometric passport stores data representative of two fingerprints of an individual.
The advantage of biometric data in terms of recognition reliability and personal security is undeniable.
Proposals have also been made to use the biometric data present in a single card to perform a variety of functions or to access a variety of services. It is thus possible to envisage biometric data stored in an identity card enabling an individual to access various different public services, such as Social Security, tax authorities, etc. Once more, the advantage in terms of reliability of authentication and of simplifying the management of identification means cannot be disputed. Nevertheless, such an identity card would then constitute a unique identity vector giving access to that individual's data as associated with the use of a variety of different services, which can lead to problems relating to protecting people's personal data.
It would thus be particularly advantageous to succeed in using the biometric data for recognizing an individual in a manner that facilitates that individual gaining access to a service, while ensuring that it is not possible to identify the individual in question from data stored by the service supplier.